1. Field of the Invention
This invention relates to medical instruments, particularly to urological probes (bougies) for dilation of the urethra.
2. Description of Prior Art
Urethral strictures, especially postraumatic ones, are very dense, rigid, and resistant to stretching. They are localized mostly in the membranous or bulbous parts of the urethra.
A non-surgical method for treating urethral strictures, known as bougienage, involves probing such strictures with elongated members or probes to enlarge them.
Such probes are known as bougies and prior-art, conventional bougies, are shown, e.g., in the textbook "Urology", 3rd ed, v.1. p. 242, M. F. Campbell and J. H. Harrison, etc. (Saunders, 1970). They comprise solid metal (or plastic) rods which are shaped to accommodate the physiological curvature of the urethra. Since in males the urethra's outer part is within the pendulus of the penis, which is highly flexible, this outer part can be bent or straightened, as necessary. The urethra's inner part extends around (behind) the pubic articulation and thus is curved. In other words, conventional bougies generally comprise a straight portion extending from the handle, followed by a curved portion adjacent to the tip. This shape corresponds to the urethra when the penis is straightened, i.e., starting at its penile outlet, the urethra is straight and then curved (roughly C-shaped).
Despite the correspondence in shapes, the insertion of a conventional bougie in males is a very complicated and painful operation, requiring high skill and concentration. Usually, the urologist will employ a set of bougies of gradually increasing diameters. The results of treatment with such instruments are not always positive, complications such as bleeding, injuries, urinary fever, prostatitis, epididymitis, etc., may occur. Even in females, whose urethras are shorter and straighter, many of these difficulties are encountered.
To obviate these disadvantages, the authors of the present invention have developed a series of new expandable urethral bougies described in the above-mentioned U.S. Pat. No. 4,705,029. These bougies comprise a probe composed of two rods pivotally connected together at one end and having a core element between the rods with wedging elements. The core element is connected to a mechanism which moves it in the axial direction so that the rods are expanded by the above-mentioned wedges, and thus expand the urethra into which the bougie has been inserted. The expandable bougie is made from a plastic material and can be supplied to urologists in a sterilized and disposable form.
Although the plastic, disposable mechanically expandable bougies are universal, convenient to use, and what is most important, can substitute a whole set of conventional bougies, they still have some disadvantages. For example, the urologist does not know whether or not the distal end of the bougie has penetrated into the bladder. Insertion of the probe into the urethra presents some problems, and in order to facilitate this procedure, it is desirable to provide the bougie with a pilot portion or leader used for guiding the bougie during its insertion into the urethra. As the probe consists of three separate longitudinal elements, i.e., two rods and a core element, these elements, especially when they are made from plastic, are extremely flexible. When the bougie is within the urethra, it is compressed or squeezed by the urethral walls. Nevertheless, the above-mentioned three elements are not locked positively, and it is possible under certain circumstances that during withdrawal of the bougie from the urethra, the core element may come out from the guide groove and traumatize the urethra.